#include <bits/stdc++.h>
#define f0r(i,n) for(int i=0;i<n;i++)
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
typedef long long int ll;
using namespace std;
vector< pair<pair<int,int>,int> > v;
map<int,vector<int>> e;
map<int,int> dep; int mx = 0;
void dfs(int u) {
for (auto v : e[u]) {
if (dep[v] < dep[u]+1) {
dep[v] = dep[u]+1;
dfs(v);
}
}
}
int main() {
int n; cin >> n; v.resize(n);
for (int i = 0; i < n; i++) {
int L, R; cin >> L >> R;
L = max(0, i-L); R = min(n-1, i+R);
v[i] = {{R, L}, i};
}
sort(all(v));
for (int i = 0; i < n; i++) {
int L1 = v[i].fi.se, R1 = v[i].fi.fi, F1 = v[i].se;
for (int j = i+1; j < n; j++) {
int L2 = v[j].fi.se, R2 = v[j].fi.fi, F2 = v[j].se;
if (L1 <= F2 && F2 < F1) continue;
if (F1 < F2 && F2 <= R1) continue;
if (L2 <= F1 && F1 < F2) continue;
if (F2 < F1 && F1 <= R2) continue;
e[i].push_back(j);
}
}
for (int i = 0; i < n; i++) {
if (dep[i]) continue;
dep[i] = 1; dfs(i);
}
for (int i = 0;i < n; i++) mx = max(mx, dep[i]);
cout << mx;
return 0;
}
